Straight through line feed vegetation trimmer apparatus

ABSTRACT

A trimmer head for use with either clockwise or counterclockwise trimmer heads, including the use of a bidirectionally dispensing spool. Various locations of passages straight through the trimmer head and spool are shown along with various locations of components of the ratcheting mechanism to allow for winding of the trimmer line on the trimmer head and for limiting the amount of line dispensed during “bumping” of the trimmer head knob on the ground. Because of the careful arrangement of the components, the trimmer head can have line wound in a single direction on the spool and still dispense line regardless of the direction that the trimmer head rotates by speeding up or slowing down the spool relative to the trimmer head housing to allow line to dispense independent of the direction of the rotation of the trimmer machine drive shaft rotating the trimmer head.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application 61/907,883, filed Nov. 22, 2013, entitled STRAIGHT THROUGH LINE FEED VEGETATION TRIMMER APPARATUS, which is incorporated herein by reference. This application is also a continuation in part of U.S. patent application Ser. No. 12/428,453, filed Apr. 22, 2009 entitled String Trimmer Configuration and Method, which claims the benefit of U.S. Provisional Application 61/071,321, filed Apr. 22, 2008, each application of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

In general, the present invention relates to string trimmers and the rotating heads of string trimmers. More particularly, the present invention relates to the mechanisms contained within string trimmer heads for winding, holding and dispensing new lengths of trimmer line when needed.

2. Prior Art Description

String trimmer machines have been commercially sold for over a quarter of a century. In this period of time, there have been many variations to the design of the string trimmer machine and especially to the trimmer head.

The trimmer head is the part of the string trimmer machine that is rotated by the drive shaft of the trimmer machine. The trimmer head holds lengths of trimmer line that rotate with the trimmer head. The rotating trimmer line contacts and cuts vegetation as it spins.

Depending upon the make, model, and manufacturer of the string trimmer machine, the trimmer head rotates either clockwise or counterclockwise during operation. The trimmer head is affixed to the string trimmer machine by a bolt or nut to the terminus of the drive shaft of the string trimmer including any extension thereto. Threading direction of the bolt or nut is determined by the rotation direction of the drive shaft so that the trimmer head does not unthread from the string trimmer during operation. The mix in the current retail market is roughly evenly split between clockwise and counterclockwise rotating string trimmer machines.

There are many types of trimmer heads on the market. The most common types of traditional trimmer heads are the bump-feed trimmer head and the automatic-feed trimmer head. Both types of trimmer heads contain an internal spool that holds a reserve of wound trimmer line. As the trimmer line wears away, it can be replaced from the internal spool. In a bump-feed trimmer head, short lengths of line are released from the spool when the bottom of the trimmer head is impacted or “bumped” against a hard surface, in an automatic-feed trimmer head, a short length of line is released from the spool without the operator having to manually strike or bump the bottom of the trimmer head on the ground. Many mechanisms exist in the prior art for controlling the release of wound trimmer line from the internal spool of a trimmer head. Bump-activated trimmer heads are exemplified by U.S. Pat. No. 5,881,464 to Collins, entitled Line Head for Flexible Line Trimmer. Automatic-feed trimmer heads are exemplified by U.S. Pat. No. 5,060,384 to Everts, entitled Automatic Head for a Line Trimmer; U.S. Pat. No. 5,109,607 to Everts, entitled Automatic Line Trimmer Head; and U.S. Pat. No. 4,566,189 to Muto, entitled Filament Type Trimmer Apparatus Cutters.

The primary problem associated with such traditional trimmer heads is one of reloading. In order to replenish and reload new trimmer line into the trimmer head, the trimmer head must typically be disassembled and the internal spool removed. This process is often too difficult for many homeowners to complete successfully or even attempt.

Another common problem that often accompanies bump-feed trimmer heads is the problem of line twisting string on the spool. Most bump-feed trimmer heads contain two lengths of trimmer line that extend from opposite side of the trimmer head. Bump-feed trimmer heads rely upon centrifugal forces to pull the trimmer lines from the spool. If the trimmer lines tangle, twist or become buried under subsequent windings or fuse together from heat, the trimmer lines may not dispense in the proper manner. The trimmer head must then be disassembled, the trimmer string unwound and again rewound in the proper manner before the trimmer head will again work as designed. Furthermore, whenever the trimmer string supply is exhausted, the trimmer head must be manually disassembled. The spool is removed and rewound with a new supply of trimmer line. The spool is then reassembled back into the trimmer head. This process is difficult, labor intensive and highly time consuming.

Another problem associated with traditional automatic-feed trimmer heads is the complexity and reliability of the release mechanism that draws trimmer line from the spool when needed. As many homeowners will attest, the mechanism for releasing the trimmer line is usually the first part of a string trimmer machine that falls to work.

Yet another disadvantage of some prior art trimmer heads is that they are designed to rotate in only a single direction, that is, the trimmer head is designed only to be mounted on a clockwise trimmer or on a counterclockwise trimmer but not both. Accordingly, a trimmer head designed for a clockwise trimmer may not work on a counterclockwise trimmer. Furthermore, some parts from a clockwise trimmer head cannot be interchanged with any of the parts from a counterclockwise trimmer head. This requires a trimmer head manufacturer to create two sets of manufacturing tools, one for clockwise trimmer heads and one for counterclockwise trimmer heads. This significantly increases the cost associated with manufacturing trimmer heads. Furthermore, it results in each trimmer head design having two different models, one for clockwise rotation, and one for counterclockwise rotation.

A need therefore exists for a string trimmer head that has an inexpensive yet reliable mechanism for dispensing trimmer line when needed. A need also exists for a string trimmer head that dispenses trimmer line with less likelihood that the trimmer line will tangle, twist, or bind. Furthermore, a need exists for a trimmer head that does not have to be disassembled to have new string added. Lastly, a need exists for a trimmer head that can be manufactured inexpensively with few operating parts and can operate either as a uni-directional of bi-directional trimmer head on trimmer machines. These needs are met by the present invention as described and claimed below.

SUMMARY OF THE INVENTION

The present invention is to a trimmer head assembly and the method of configuring the trimmer head assembly. The trimmer head assembly attaches to a string trimmer machine. The trimmer head assembly holds lengths of trimmer line that cut vegetation when the trimmer head assembly spins and contacts the vegetation.

The trimmer head assembly has a housing that attaches to the string trimmer machine. A spool is provided inside the housing. The spool rotates about an axis of rotation. The spool can move longitudinally along the axis of rotation between at least a first position and a second position. A ratcheting mechanism and an indexing mechanism are provided between the trimmer head housing and the spool. When the spool is in its first position, the ratcheting mechanism enables the spool to continuously or discretely rotate about the axis of rotation in the direction opposite that in which the trimmer head assembly spins. The ratcheting mechanism also prevents the spool from rotating within the housing in the either direction when unintended and only allows rotation in the trimmer line winding direction when sufficient torque is applied.

Using the ratcheting mechanism, new trimmer line can be wound onto the spool, simply by anchoring the trimmer line to the spool and manually turning the spool. No disassembly is required. Preferably the string/line can be fed straight through from one eyelet to the other eyelet (“straight through”) prior to winding the line onto the trimmer core.

In operation, an activation mechanism is provided for momentarily moving the spool from its first position in the housing to its second position. The activation mechanism can be automatic or bump activated. Once momentarily in its second position, the indexing mechanism enables the spool to turn so that a small length of the trimmer line can unwind from the spool.

It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.

For the purposes of this application, a “bidirectionally-operable trimmer head” is defined as a trimmer head that can be assembled with the line (subsequently or previously) wound around the trimmer head spool and mounted to either a clockwise trimmer machine or to a counterclockwise trimmer machine, wherein the trimmer head will dispense line outward when activated regardless of whether the trimmer head is currently rotating in the clockwise or counterclockwise direction because the spool can rotate in a direction independent of the trimmer head to dispense a length of line outwardly. In a bump-activated trimmer head, the centrifugal force on the line overcomes the rotational forces on the spool to allow it to rotate in the direction to release an amount of trimmer line even if the spool rotation direction is opposite to the current trimmer head rotation direction during line dispensing and the spool rotational velocity is faster than the trimmer head rotational velocity when both are rotating in the same direction. A “wound trimmer head” is defined as a trimmer head having a trimmer line wound on the spool thereof.

It is an object of the invention to provide a bidirectionally-operable trimmer head for mounting the same assembled, wound trimmer head for use with either a clockwise or counterclockwise trimmer head.

These and other objects of the present invention will be readily apparent upon review of the following detailed description of the invention and the accompanying drawings. These objects of the present invention are not exhaustive and are not to be construed as limiting the scope of the claimed invention. Further, it must be understood that no one embodiment of the present invention need include all of the aforementioned objects of the present invention. Rather, a given embodiment may include one or none of the aforementioned objects. Accordingly, these objects are not to be used to limit the scope of the claims of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a trimmer head according to a first embodiment of the invention.

FIG. 2 is an exploded view of several of the components of the trimmer head of FIG. 1.

FIG. 3 is a perspective view of the trimmer head spool of FIG. 11.

FIG. 4 is an exploded view of the trimmer head of FIG. 1.

FIG. 5 is a cross-sectional view of an alternative version of the trimmer head of FIG. 1.

FIGS. 6-8 show views of a trimmer head according to a third embodiment of the invention having a center flange.

FIGS. 9-12 show views of a trimmer head according to a further embodiment of the invention having a flangeless spool.

FIGS. 13-14 show views of a trimmer head according to a further embodiment of the invention having passages in the bottom flange of the spool.

FIG. 15 shows an alternate spool having multiple passages therethrough for use with at least one embodiment of the invention.

FIGS. 16-20 show views of a trimmer head according to a further embodiment of the invention having a non-circular spool.

FIG. 21 shows an alternate spool having spokes instead of a center flange for use with at least one embodiment of the invention.

FIGS. 22 and 23A-B show alternate spools having multiple passages therethrough for use with at least one embodiment of the invention.

FIG. 24 shows a trimmer head according to a further embodiment of the invention having a modular passage through the center of the spool.

FIGS. 25A-E shows alternate modules having various passageways through the center of the spool for use with at least one embodiment of the invention.

FIGS. 26A&B and FIG. 27 show various components of the trimmer head of FIG. 24.

FIGS. 28A&B show an alternative spool arrangement having passages through the bottom flange for use with at least one embodiment of the invention.

FIG. 29 shows an alternative spool having no passages through a flange of the spool for use with at least one embodiment of the invention

Similar reference characters denote corresponding features consistently throughout the attached drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention relates to straight through feed trimmer heads for string line trimmers.

FIGS. 1-4 shows a sectional view of a first embodiment of a trimmer head 10 for use with a string trimmer machine (not shown). The trimmer head affixes to a string trimmer machine drive shaft arbor (including any extension thereof,) (not shown) by a bolt, nut or other fastener 12 in a form and specification as required to mate with the respective arbor. Typically, the direction of threading of the fastener is selected so that during normal rotation of the drive shaft, the fastener will tend to tighten rather than loosen from the arbor. The fastener 12 allows the trimmer head 10 to rotate as a unit with the drive shaft to drive a trimmer head line 14 in a radius outwardly from the trimmer head. The trimmer head line 14 is well known in the art and may be made of plastic or other material and is rotated at a high speed to cut grass, weeds or brush that the line comes in contact with and is available in a number of line diameters. U.S. Pat. No. 8,025,249 issued Sep. 27, 2011 to George Alliss shows one such configuration and operation of a string trimmer head, which patent is incorporated herein by reference.

The upper housing 21 includes a non-circular “keyed” chamber 23 (FIG. 4) for receiving (or acting as) the fastener 12 and to prevent the fastener from rotating relative to the housing. The chamber 23 is shown as being octagonal, but the shape may be chosen to accommodate whatever fastener is used to connect the housing to the arbor. The fastener is typical a bolt or nut is forward or reverse threading.

A core 16 is provided within the trimmer head 10 to receive the trimmer line thereabout as it is wound into the trimmer head. The core is selectively rotatable relative to the housing. A pair of eyelets 18 are provided on the outer housing 20 to introduce the trimmer line into the interior of the housing. The eyelets are preferably 180 degrees apart from each other, but in some circumstances may be more or less than 180 degrees apart and may include fewer or more eyelets. The eyelets may include a metal guard or other sleeve for resisting wear as the line 14 within the eyelet is moved about or through the eyelet.

The core preferably may have a central opening or chamber defined by inner wall(s) 22. Preferably the trimmer core 16 preferably includes a central, straight through guide passage (“channel”) 24 therethrough. The passage 24 preferably has a first opening selectively alignable with (or being positioning relative to) one of the pair of eyelets 18 of the housing to feed a trimmer line therethrough and a second channel opening alignable with the second of the pair of eyelets 18 when the first opening is aligned with the first eyelet. The alignment of the channel and eyelets allows a trimmer line to be fed from the first eyelet through the first channel opening, through the channel and out through the second opening and second eyelet when feeding the trimmer line onto the trimmer head. An indicator 31 (FIG. 4) viewable from outside the trimmer head may be provided so that the user is aware when the core 16 and housing are aligned and ready for receiving the line. In a preferred embodiment, the indicator is on the knob viewable from beneath the trimmer head.

FIG. 2 shows a preferred configuration of the core of the trimmer head. In order to wind and release trimmer line from the trimmer head, a ratchet system and an indexing system are provided. The ratchet system includes a first system for winding the trimmer line. The figure shows the trimmer head core 16 with a trimmer line 14 fed therethrough. A knob 30 for engaging and rotating the core 16 is shown below the core. A lower housing 32 which forms part of the outer housing 20 is shown below the knob. The knob 30 has a number of preferably non-circular arms/splines 34 which are received within a mating receiver of the core 16 to securely rotate the knob and core together when required. The lower housing 32 cooperates with the upper half of the housing 20 to secure the knob and core therein with a portion of the knob 30 extending through an opening 33 in the lower housing. The upper 23 and lower 32 housing may be connected by a number of methods or systems, but are preferably connected by a quick release system such as by flexible arms/fingers 25 and cooperating holes 27 interference fit with each other.

Additionally, the core and upper and lower housing cooperate to form an indexing system and ratchet mechanism for feeding and controlled release of the trimmer line. In the position shown in FIG. 1, the eyelets 18 and feed channel 24 are aligned allowing a length of trimmer line 14 to feed through the outer housing through the core and out the other side. The knob 30 can be rotated to wind the line onto the core 16. The core has an upper disk 36 and a lower disk 38 which form upper and lower boundaries of the lower chamber 57 for the trimmer line to be wound on the core. The upper chamber 59 is formed by the upper disk 36 and a shelf 61 of the housing as describer later hereinunder. As shown in FIG. 3, the openings 40 of the feed channel 24 have an opening on the side for directing the line onto the core. As the core is rotated clockwise in the FIG. 3, the line will resist turning by friction, inertia and other forces acting on the line outside of the housing 20. The core will turn away from the trimmer line entrance, and the inner wall 42 will begin to pull the trimmer line as the core continues to turn. The line will then begin to be pulled into the housing as the line wraps around the inner wall 42 of core 16. As the user continues to rotate the core via knob 30, cogs 44 on the lower disk 38 will rotate. A number of ramps 46 on the lower housing are arranged to interfere and impede the rotation of the cogs within the housing during normal operation of the string trimmer machine. It should be noted that a spring 50 is provided above the core to bias the core downward but which allows for axial movement of the core (and attached knob) under a preselected force.

One purpose of the obstructions is so that the core cannot “freewheel” when the housing is turned by the string trimmer. It is desired that the core and housing turn together during normal operation so that the trimmer line is maintained at a constant length. If the core were allowed to turn, then the trimmer line could unintentionally wind or unwind as the housing turned relative to the core.

In order to continue to wind the line onto the core, the user applies enough torque on the knob to force the cogs 44 of the core past the ramps 46. The ramps are oriented such that rotation in the proper direction (in the example, clockwise, but one skilled in the art would recognize that the ramps could be arranged to rotate only clockwise, only counterclockwise or in both clockwise and counterclockwise directions by having one ramp or by having two opposing ramps back to back) causes the cog to move up and over the ramp. When turned in the opposite direction (for one way ramp configurations), the cog will strike a vertical wall of the ramp (or other similar obstruction) and further torque will not promote further rotation of the knob and core. As the cog moves up the ramp, the core 16 will move axially upward compressing spring 50. As the cog moves up and over the ramp, the spring will then force the core axially downwardly with the cog axially aligned with the next ramp. This ratcheting system allows the direction of winding to be controlled and also provides a control for allowing only a certain amount of line to be released. One way ratcheting has the advantage of ensuring that the line only winds one way onto the core and the line cannot be “fouled” by turning the core in the “wrong” direction.

The trimmer line during winding will be forced into one of two chambers 57, 59. The side port opening 41 of the passage determines whether the particular end of the line will wrap into the lower chamber 57 or upper chamber 59. As shown in the front of the FIG. 3, the port 41 at the front directs line into the lower chamber 59 which is bound by upper and lower flanges 36,38 (FIG. 3). The rear port 41 (FIG. 2) directs line 14 onto the upper chamber. The upper chamber in this embodiment as best shown in FIG. 2 is bound at the lower end by upper flange 36 and at its upper end by a surface/shelf 61 of the housing 20. Preferably the shelf 61 is smooth to reduce any drag or friction of the trimmer line on the shelf as the spool rotates relative to the housing. The interior wall of the chamber is preferably provided by the core of the flange which rotates about the circular wall 65. Similarly the lower edge of the spool may rotate while being supported for rotation by a lower circular wall 67 of the housing which encloses the spool or both the spool and knob (“activation mechanism”).

As is known in the art, the user taps the string trimmer head on the ground to release an amount of string. In the present invention, this is accomplished by depressing the knob further into the housing (“axially upward”) causing the core 16 to move upwardly against the bias of the spring 50. The axial movement is sufficient to raise the cogs 44 of the core 16 above the ramps 46. This frees the core 16 to free spin relative to the housing 32 in either direction. The direction of the spin (relative to the housing) will be controlled by the forces on the trimmer line 14 and the direction that the line is wound on the core, not by the direction of the trimmer head. This results in a bidirectionally operable trimmer head that can be mounted to a clockwise or counter clockwise trimmer head regardless of the direction the line in wound on the trimmer head. Regardless of whether the trimmer head is spinning clockwise or counterclockwise, the forces on the trimmer line will act to pull the line outward as the centrifugal force on the line pulls the line outwardly. The outward force will act to unwind the line by pulling the line and rotating the core in the proper direction to unwind the line. Since the cogs are temporarily axially upward of the ramps 46, the core is free to spin in either direction (relative to the housing) and will move in the proper direction to unwind the line regardless of the direction of rotation of the trimmer head.

Another function of the trimmer head is to control the amount of rotation during the free spin when feeding line outward. This is desirable so that only a small bit of line is fed out to replace line that has been worn down or cut during trimming of brush or weeds. The user can repeat the process described by “bumping” the knob again if further amounts of line are needed. The line control indexing feature in the embodiment illustrated is performed by a number of upward protrusions 52 (“square teeth”) provided on the upper area of the core. The amount of string/line 14 released during one bump is controlled by the spacing between stop bars 54 on the upper section 21 of housing 20. The core 16 may rotate in the free spin mode at most until the protrusions hit one of the stop bars halting the rotation of the core. As soon as the pressure on the knob is released the core will drop back down to its original axial position under the bias of spring 50. The core may then rotate until a cog 44 runs into an interfering ramp. The centrifugal forces on the line will prevent the cog from further turning up the ramp which would cause the trimmer line to retract onto the spool. A cog turning the opposite direction would strike the vertical wall of the ramp and would thereby be prevented from rotating further. In this way, bumping the knob will allow the core to free spin relative to the housing, but the amount of (bi-directional) free spin will be controlled by the teeth 52 and stop bars and the spring will return the core to the original axial position where the ramps will prevent the core from turning past a ramp by the interaction of the ramps and cogs. It should be noted that even if the teeth do not hit the stops, the bias of the spring will bring the cogs and ramps back into align acting as a failsafe to prevent unintended amounts of line from being released in a single bump.

Bidirectional dispensing. A result of the specific organization of the trimmer head is that once the line is wound on the trimmer head, the trimmer head can dispense line properly no matter which way the trimmer head is rotating. Typically the trimmer line is wound on a trimmer head so that hitting the knob/bump on the ground slows the spool relative to the housing. The housing can thus rotate to unwind the line from the spool as the eyelets contacting the trimmer line unravel a length of line from the spool. The current trimmer head has a separate mode where the spool can also speed up relative to the trimmer head housing to “push” the line outward. In actuality, it is the centrifugal force on the line from the length of the line outside the housing plus the frictional contact of the line with grass or weeds or other material that pulls the line against the spool causing tension in the trimmer line. Trimmer heads built in accordance with at least one aspect of the present invention allow the spool to “free wheel” relative to the housing for a brief interval. During this interval the line can actually pull the spool faster than the housing to release an amount of line. Preferably, one of the stops prevents an undue amount of line from being released at the time. This ability to release the line by being able to both speed up relative to the housing or to slow down relative to the housing during dispensing of the line outwardly from the spool to allow the spool to dispense trimmer line independent of the direction of rotation of the trimmer head is defined for the purposes of this application as “bidirectional dispensing” or “bidirectional line dispensing.” A trimmer head that is capable of bidirectional dispensing is “bidirectionally operable.” The direction of winding of the line on the trimmer head is defined herein as the direction in the line would be wound relative to the spool to release/dispense trimmer line when the spool slows relative to the trimmer housing, i.e., winding a trimmer line clockwise on the spool would allow a counterclockwise rotating trimmer head to dispense line from the spool when the knob is “bumped” on the ground to slow the spool relative to the housing to allow the housing to unwind a length of trimmer line to dispense that length of line outward through the eyelet of the housing as the housing rotates counterclockwise faster relative to the spool.

FIG. 5 shows an alternative construction for the first embodiment. In this configuration, the ratchet on the bottom of the lower disk 38 are formed by teeth or gears 60 and the ramps 62 on the lower housing 32 have been moved inwardly to accommodate the location of the gears 60. One skilled in the art would recognize from the teachings of the present invention that the functional components of the ratchet (stop bars, teeth/gears, and ramps) could be located on any of the various surfaces of the core as needed to perform the function of providing a winding ratchet and a line feed control function without departing from the scope of the invention.

FIG. 24 shows an alternative version of the invention according to a further embodiment. The spool 2416 is splined to knob 2430 through spline 2434 and cooperating slots and grooves on the knob 2430 so that the spool and knob will co-rotate together. FIGS. 26A&B show the combined spool and knob 2433 and profiles of the ramps and cogs thereon. Ramps, stops and cogs are each preferably provided to allow the spool to wind spool in a particular direction and to index the amount of line dispensed can be controlled. A feature shown in FIG. 24 that can be used with any of the other embodiments is a module 2470 that can be installed within the spool 2416. The module aligns with the passages 2440 of the spool and provides/controls routing of the trimmer line within the core of the spool from one flange passageway to the other flange passageway. The module may have a key, tooth, spline, groove or other device so that it is aligned properly with the spool. The module may be reversible or rotatable to change the orientation, path or alignment of the module with the spool. The module is preferably switchable with other modules to control the path through the core to route the line in various paths. The module provides flexibility such as routing around a driveshaft, bolt or other similar device (if any) by providing a curved path 2472 (FIGS. 25A&B) or to route straight though the center 2470 (FIG. 24). Depending on the shape of the path through the flange (or wing), additional paths could also be used. FIG. 25C shows a one-sided curved path 2474 that leads through a corresponding spool flange (not shown). FIG. 25D shows a spiral path through the center of the module 2476 that leads to a corresponding spool flange having spiral, non-radial passages therethrough (not shown). FIG. 25E shows a module 2478 having a plurality of passage for use selectively with 1-2 trimmer lines through a cooperating flange having corresponding passages (not shown) for each of the two module channels. FIG. 27 shows a module 2470 installed within the spool 2416.

FIGS. 28A&B show an embodiment of the invention similar to that of FIG. 1, however the channels 2840 are provided in a lower flange instead of the upper flange 40. One skilled in the art would appreciate that the eyelets 2818 of the housing would have to be aligned with the lower flange in this embodiment instead of with the upper flange. Preferably the cogs 2844 are also reversed from the bottom flange to the top flange.

FIGS. 6-8 show another embodiment of the invention having an example of variation in the placement of the ratchet components and includes a central flange for dividing the trimmer line into an upper and lower chamber. In FIG. 6, a central core 116 of a trimmer head 110 has a number of cogs 152 on an upper disk 138 that cooperate with a number of stops 154 (FIG. 7) provided in the upper portion 121 of the housing. The followers 144 on core 116 and ramps 146 on lower housing 132 cooperate to form the trimmer line winding ratchet. The spring 150 biases the core 116 into proper axial position as discussed above. In this embodiment, the knob 132 is preferably formed as an integral part of the core 116.

The core 116 has a different configuration for accepting an amount of trimmer line onto the core 116 into two separated chambers. By separating trimmer line as it is fed in through the left and right eyelets 118 into separate chambers, there is less chance that the line will tangle with itself and can avoid line “fusing” to itself. Because trimmer line can be thicker and stiffer than for example “fishing line,” the line can tend to straighten itself out (“unspool”) in the trimmer head and then tighten in use. These cycles can cause the line to wind on itself or even weld/fuse to itself under the heat of friction. Separating the lines can lessen the chance of these problems and increase the ease and reliability of feeding out line during operation. To facilitate the line winding onto the two chambers (instead of all the line feeding into on chamber), the openings 140 on either side on the center flange 137 open on diverse sides of the flange. One opening has its mouth 141 opening above flange 137 to feed line into the chamber formed between the upper disk 136 and flange 137. The opposite opening 40 is the mirror image with a mouth opening towards the bottom of flange 137 to feed line into the chamber formed by flange 137 and disk 133.

In operation, knob 130 is rotated to cause followers 144 to rise up and over ramps 146 to allow the core 116 to rotate relative to the housing 121,132. The rotation of the core causes line fed through the housing eyelets 118 through the trimmer line feed channel opening 40 and out the opposite eyelet to wrap around the core 116. Because of the varied orientation of the mouths of openings 140, different portions of the line will wrap into the individual chambers formed above and below flange 137. When trimmer line is required to be fed out to increase the length of the active cutting section of the line, the use will strike (“bump”) the knob on the ground of other surface. The bump will cause the followers 144 to lift above ramps 146, and centrifugal on the trimmer line will cause the line to pull against the core to rotate the core in the direction (relative to the housing) necessary to feed the line outward, regardless of the overall rotational direction of the trimmer head. The rotation of the core relative to the housing will be checked by the cogs 152 striking the stops 154 to control the amount of line fed during one “bump” of the knob 130.

FIGS. 9-12 show an alternative embodiment having a flangeless core and which distributes some of the ratcheting components to a knob separated from the core. FIG. 9 shows an exploded view of the trimmer head 210. The core 216 is rotatingly tied to the knob 230 by arms/splines 233 engaged with corresponding slots 235 that will cause the knob and core to fixedly co-rotate together. The knob and core and bias spring 250 are located and biased into position between the lower housing 232 and upper housing 221. A number of square teeth 252 cooperate with corresponding stops on the upper housing 221 to form the feed control (“indexing”) mechanism as described above to limit the amount of line fed out during “bumping” of the trimmer head knob 230.

The upper housing 221 has a guide wall 253 (FIG. 12) for receiving the outer wall of the core. The guide wall serves a number of purposes. Firstly, it centrally locates the core 216 within the housing. With the knob 230 centered in lower housing 232 and the core located in the upper housing 221, the core and knob will be guided to rotate securely within the housing about a fixed axis. Additionally, the guide wall causes the square teeth 252 to properly align with stop bars 254 as described above. The stops and teeth will limit the amount of free rotation of the core during “bumping” and will only dispense a limited amount of line per bump, it should be noted that while the wall 249 of the upper housing 221 is shown as surrounding and securing the core 16, it is preferable that the wall 249 is provided within the core (see for example, FIG. 1) so that the core can rotate about the wall 249. This allows the line to wrap around the upper section of the core instead of around the upper housing wall 249, which lessens the friction on the line as the core rotates independent of the housing 221.

The lower housing includes a number of followers 244 that cooperate with the ramps 246 (FIG. 11) to provide the ratcheting function to allow winding of the trimmer line onto the core 216 while preventing unintended rotation of the core relative to the housing. In operation, the spring 250 biases the core downwardly. The core 216 presses down on the knob, which forces the ramps 246 and followers 244 into axial alignment. Rotation of the core rotates the knob until the ramps engage the followers. If the torque on the knob is increased, such as by manually turning the knob 230, the followers will force the ramps upward against the bias of the spring 250. If enough torque is applied, the ramps will pass over the followers 244 and the spring will force the ramps back down into alignment with the followers in a ratchet-like motion. The rotation allowed by passing the ramp over the follower will allow the core to rotate relative to the housing to wind additional line around the core. The axial spacing of the ratchet mechanism may be such that the height that the knob moves as the ramp goes over the follower is insufficient to bring the square teeth 252 into engagement with the stop bars 254 and thus the stops will not interfere with the rotation of the core during winding of the line onto the core as the knob is rotated.

The core 216 itself is flangeless. It does not require an upper or lower disk or a central flange to coordinate the winding of line onto the core. The core has a number of arms 217 that extend the length of the trimmer line feed channel 224 from one eyelet 218 to the other. The channel terminates into opposing openings 40. The opening on one side of the channel has a mouth 41 opening upwardly and the other opening has a mouth opening downwardly. Line fed upwardly feeds into an area of the housing bounded by the arm 217 and the upper housing 221. The guide wall 253 prevents the line from interfering or entangling with the rotating core or with the square teeth 252 at the upper end of the core. Line fed downwardly feeds into an area of the housing bounded by the arm 217 and by the lower housing 232. Additional line that feeds in as the core rotates past the eyelet again continues to wind onto the proper area above or below the arm 217 because the line is pulled above or below the eyelet by the length of line already within the housing. The distance that the walls 249 of the opening of the channel extend above the arm, for example, helps ensure that further line will also be fed in above the arm since that section of the line is already biased in that direction pulling the line above (or below as needed) the arm. In this way, the core does not require a top, bottom or center flange to control the orderly storage and maintenance of line within the trimmer head housing.

FIG. 21 shows an alternative embodiment of the invention having an upper and lower flange, but no center flange. The spool 2116 has an upper flange 2136 and a lower flange 2138. This could for example be used in place of the spool of FIG. 6. Appropriate cogs, ramps and/or stops could be provided as necessary to mate with ramps, cogs or stops on the housing. A bump knob (not shown) could be provided that would mate at the bottom of the spool or provided integral to the spool. In operation, a line fed through the opening 2140 would be fed through the other side to openings (118, FIG. 6) in the housing.

As the spool was rotated, the line would feed out the side openings 2141 of the spoke or wing 2117 and would wind around the central wall 2111 of the spool. A flange is not required because the spokes would act to separate the line into the top or bottom opening according to whether the channel opening 2141 opened to the top or bottom of the wing 2117. In practice, during the next rotation around the line in the top chamber will be taught and spaced above the top 2119 of the spoke 2117. The spoke can be flared (expanded in the radial direction) to help ensure that the line wraps in the proper direction. This will act to pull the next bit of line still above the wing so that it also wraps in the top chamber. Line in the bottom chamber will analogously wrap in the bottom chamber. The top and bottom flanges will act to maintain the line on the spool. Additional spokes or wings could be provided about the core of the spool. These additional spokes could have passages therethrough to allow additional trimmer lines to be used or can be used as alternate passages in case the primary passage through the spool is blocked by a broken line or the like. The additional spokes could also be provided without passages (not shown) therethrough to help ensure that the line continues to wind into the proper channel as line control spokes. The spool will otherwise act in a similar mode to that of FIG. 6.

FIGS. 13-14 show a further embodiment of the invention. FIG. 13 is a cross-sectional view of a trimmer head 310 utilizing a core 316 having no bottom flange. As seen in FIG. 14, the core 316 has a central flange 317 with a straight through trimmer line feed channel 324. An upper disk 336 (FIG. 14) carries cogs 352 that cooperate with stops 354 on the upper housing 321 to form the trimmer line dispensing control mechanism. The channel 324 terminates in a pair of opposed openings 340. One opening biases trimmer line into a chamber formed between the upper disk 336 and the central flange 317. The opposite opening has a mouth that biases that section of trimmer line downward to the area of the housing formed between the flange 317 and the interior of the lower housing 332 and the knob 330. The knob may have an upper surface (“shelf”) 339 to prevent line accumulating thereon from spreading into unintended areas during rotation and to define a lower chamber for receiving line therein. A lower tubular portion 374 of the core 316 may be provided to extend into knob to further secure the core to the knob and to promote rotation of the core about the central axis of the trimmer head. Since the core 316 and the knob are fixed together by a slot 370 and groove 372 on the core extension 374, the line will rest on the upper surface as the knob and core co-rotate therewith. To release trimmer line, ramps 346 on the knob cooperate with followers on the lower housing (see FIG. 9, reference 244) to allow the trimmer line to be wound onto the core 316 as discussed above.

FIG. 15 shows an alternative embodiment of a trimmer head having more than one trimmer head feed channels 424 (“passage”). The core 416 provides a number of feed channels 424. The channels may be connected to the appropriate opposing or adjacent channel by passages 420 in a central module 422 in the core 416 so that the line fed through one channel 417 feeds out of a second channel in the core 416. See fig. The number of lines that can be fed through simultaneously is controlled to one line by the number of eyelets on the outer housing (see for example, FIG. 1) and is typically only one line. However, it may be desirable to provide additional channels on the core 416 for various reasons including in case one channel gets blocked by broken line or debris. Additionally, channels could be provided to receive different types/diameters of trimmer lines or for other purposes. The channels could cross each other in the middle so that are in communication with each other or one or more of the channels could each bend slightly so that the channels cross over each other. Depending on the requirements of the core 416, the openings on each channel could cause the line to all flow into one chamber or to divide onto either side of the channel. The channels could be configured alike or in different configurations as needed. The multiple channels could be provided on a central flange or on a top or bottom disk or on a flangeless core. FIG. 22 shows a similar four channel spool 2216 having four channels/passages 2217 in a central flange. Preferably, the channels openings at the opposite end of the passage would lead into the same chamber to separate the winding of the two trimmer lines.

FIGS. 23A&23B show spools 2316 having passages 2317 in a top flange and in a bottom flange respectively. The spool and trimmer housing could also be configured to have passages in both of the top and bottom flanges at the same time to provide for the attachment of multiple trimmer lines or to provide an alternative mounting spot for a trimmer line when one passageway is blocked. A central flange could be provided so that both ends of the trimmer line from the top flange are stored in the top chamber and both ends of the trimmer line from the bottom flange are stored in the bottom chamber.

FIG. 29 shows an alternative version of the spool 2916. In this embodiment there is no path/channel/passage through the center flange. Instead, there are two passageways extending through the spool, each 90 degrees from each other, so that two trimmer lines can be extended through the spool. Each passageway has a terminating opening/hole 2940 at each end of the passage. The opening 2940 in the core of the spool determines whether the line will wrap into an upper chamber or into a lower chamber. Preferably, the hole at the opposite end of the passage would lead into the same chamber to separate the winding of the two trimmer lines. The drawback to this design is that it may require an artificial aid to thread the line through the eyelet and through the spool. This could be accomplished several ways including the use a straw or other device or by disassembling the trimmer head to thread the line properly. For these reasons, this design is less preferable to other designs, but may accomplish goals at a lower cost, for example.

FIGS. 16-20 show an additional embodiment according to at least one aspect of the invention having a non-tubular core. FIG. 18 is a cross-sectional view of the trimmer head 510. The trimmer head 510 includes an upper housing 521 (FIG. 19) and a lower housing 532 (FIG. 20) with a core 516 (FIG. 16), a spring 550 and a knob 530 (FIG. 17) housed therein.

The upper housing 521 has a keyed chamber for receiving a fastener to connect the trimmer head 510 to the arbor of a string trimmer machine. The housing interior is shaped through a number of spacers 519 around the wall to receive the outer diameter of the flange 517 so that the core 516 rotates within the housing about a central axis. That is, the core can rotate without undue wobbling, etc. The housing has a number of eyelets 518 that may include metal or plastic guards or sleeves to prevent wearing of the housing as trimmer line 514 is added to or removed from the housing. The upper housing 521 is connected to the lower housing as appropriate.

FIG. 20 shows the lower housing having flexible collet-like fingers 525 that secure within openings 527 within upper housing to provide a quick release connector between the upper and lower housing. Pressing the fingers 525 inwardly releases the fingers from the openings 527 so that the housing can be separated into the upper and lower housing parts. Likewise, knob 530 can be secured to the core 516 by fingers 76 cooperating within openings 576 on the core or by other fasteners or threading. The walls of the key 578 on the knob are dimensioned and shaped to fit within an opening on the bottom of the core 516. Preferably the opening is the same shape and dimensions as the inner walls 578 of the core to securely receive the knob so that the knob cannot rotate relative to the core. One skilled in the art would recognize that the invention could be practiced regardless of the shape chosen for the knob's key and the corresponding opening in the core as long as they can cooperate with each other.

The core has a center flange 517 for separating the incoming halves of the trimmer line 514 into a lower chamber formed between disk 538 and flange 517. Trimmer line above the flange 517 is retained within the space between the flange 517 and the upper housing 521. The trimmer line as discussed above is fed from outside the housing through an eyelet 518 through the channel 524 and out the other eyelet. The line is then fed onto the core by turning the knob, which rotates the core 516 to wrap the line around the core. Cooperating ramps 546 and followers 544 control unintended rotation of the core relative to the housing, while allowing desired rotation by turning the knob with sufficient torque to cause the ramps to move past the followers for the desired amount of travel as discussed above.

The presently described embodiment preferably does not include an indexing system having separate stops and cogs or square teeth. The stops are utilized in some of the embodiments to control the amount of line fed through the eyelets per “bump” of the knob. It has been found that the amount of line fed out during a “bump” can be adequately controlled simply from the ramps and followers. When the knob is bumped or pressed by a quick tap of the trimmer head on the ground, there may be a small time gap before the core actually begins to turn. If the rebound force of the spring 550 is specified properly and the number and positioning of the ramps is properly built into the trimmer head, then the return time that it takes to press the core back down into the original position and place the ramps on or between the followers is sufficient to only allow a small amount of rotation of the core before the ramps hit a follower and stop rotation of the core relative to the housing. In this way, the use of only the ramp and follower portion of the ratchet system is sufficient to perform both functions of allowing winding and controlling trimmer line feed.

It will be understood that the embodiments of the present invention that are illustrated and described are merely exemplary and that a person skilled in the art can make many variations to those embodiments. For instance, the number of cog projections, ramp projections and stop projections can be varied provided the numbers for these elements remain equal. Likewise, the shape of the bump knob, the shape of the housing and the shape of the spool can be varied into numerous configurations that are not illustrated. All such embodiments are intended to be included within the scope of the present invention as defined by the claims. None of the embodiments need include any or all of the features of the invention.

While this invention has been described as having a preferred design, it is understood that it is capable of further modifications, uses and/or adaptations of the invention following in general the principle of the invention and including such departures from the present disclosure as come within the known or customary practice in the art to which the invention pertains and as maybe applied to the central features hereinbefore set forth, and fall within the scope of the invention and the limits of the appended claims. It is therefore to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims. 

I claim:
 1. A method of dispensing trimmer line from a bidirectionally operable trimmer head comprising: providing a bidirectionally operable trimmer head with a spool rotatably mounted within a trimmer head housing; said spool having at least one chamber for winding trimmer line threaded through said spool and around the spool in a first winding direction; mounting the bidirectionally operable trimmer head to a trimmer machine having a drive direction in the same direction as the first winding direction: providing said trimmer head with a pair of eyelets for receiving the ends of the trimmer line therethrough from said spool to an area outside of the housing; routing trimmer line through one of said eyelets through said trimmer head and out a second one of the pair of eyelets; providing an activation knob slidably connected to said trimmer head housing for moving said spool from a first axial position relative to said housing to a second axial position relative to said housing to a second axial position relative to said housing; providing said trimmer head with a ratchet mechanism selectively switchable between a first winding mode when said trimmer head is in a first axial position for only allowing manually rotating said activation knob to wind the trimmer line from outside the housing onto said spool in the first winding direction while preventing rotation in a rotational direction opposite of the first winding, and providing said trimmer head with a second bidirectional line dispensing mode when said trimmer head is a second axial position for dispensing a length of the trimmer line out through the pair of eyelets; winding the activation knob to wind the trimmer line onto to the at least one chamber of the spool in the first winding direction; operating the trimmer machine to cause the trimmer head housing to rotate in the first winding direction; activating the activation knob at least once to switch the ratchet mechanism into the second bidirectional line dispensing mode to cause the trimmer head housing to slow relative to the spool to dispense line wound on the spool out of the pair of eyelets during each activation of the activation knob.
 2. The method of dispensing trimmer line from a bidirectionally operable trimmer head of claim 1, wherein after the activation knob is activated both the spool and the trimmer head slow down and the spool accelerates quicker than the housing due to tension forces on the trimmer line pulling on the spool.
 3. A bidirectionally operable trimmer head for selectively mounting to either one of both a trimmer machine having a clockwise drive direction and a trimmer machine having counterclockwise drive direction, comprising: a trimmer head having a spool rotatably mounted within a trimmer head housing; said spool having at least one chamber for winding trimmer line threaded through said spool and around the spool in a first winding direction; said trimmer head having a pair of eyelets for receiving the ends of the trimmer line therethrough from said spool to an area outside of the housing; an activation knob slidably connected to said trimmer head housing for moving said spool from a first axial position relative to said housing to a second axial position relative to said housing; said trimmer head having a ratchet mechanism selectively switchable between a first winding mode when said trimmer head is in a first axial position for only allowing manual rotation of said activation knob to wind the trimmer line from outside the housing onto said spool in the first winding direction while preventing rotation in a rotational direction opposite of the first winding, and said trimmer head having a second bidirectional line dispensing mode when said trimmer head is a second axial position for dispensing a length of the trimmer line out through the pair of eyelets; wherein said spool includes a replaceable module within said spool for routing said trimmer line straight through said spool in a radial direction when a first module is in said spool and for routing said trimmer line through said spool in a non-radial direction when a second module is in said spool.
 4. The bidirectionally operable trimmer head of claim 3, wherein when said ratchet mechanism is in second bidirectional line dispensing mode, said spool slow downs relative to said trimmer housing to dispense trimmer line out of the pair of eyelets when said trimmer line is wound in the opposite direction of rotation of the trimmer machine drive direction and said spool speeds up relative to said trimmer housing to dispense trimmer line out of the eyelets when said trimmer line is wound in the same direction of rotation of the trimmer machine drive direction.
 5. The bidirectionally operable trimmer head of claim 3, wherein said module is removably mounted to said spool by a quick connect mechanism.
 6. The bidirectionally operable trimmer head of claim 3, wherein said spool includes a top flange and a bottom flange defining a spool storage area, and wherein said trimmer line is threaded through said spool within a passage way contained within the top flange of said spool.
 7. The bidirectionally operable trimmer head of claim 5, wherein said spool includes a top flange and a bottom flange defining a spool storage area, and wherein said trimmer line is threaded through said spool within a passage way contained within the bottom flange of said spool.
 8. The bidirectionally operable trimmer head of claim 3, wherein the activation knob is non-rotatably connected to said spool by a cooperating spline on said spool and a ridge within said activation knob.
 9. The bidirectionally operable trimmer head of claim 3, wherein activation knob is non-rotatably connected to said spool by a cooperating spline on said activation knob and a ridge within said spool.
 10. The bidirectionally operable trimmer head of claim 3, wherein the at least one chamber is defined at its lower end by a first flange on the spool and at its upper end by a wall of the trimmer head housing.
 11. The bidirectionally operable trimmer head of claim 10, wherein the spool includes a second chamber defined at an upper end by a first flange on the spool and at a lower end by a wall of the trimmer head housing.
 12. The bidirectionally operable trimmer head of claim 3, wherein the at least one chamber is defined at its upper end by a first flange on the spool and at is lower end by a wall of the trimmer head housing.
 13. The bidirectionally operable trimmer head of claim 3, wherein the at least one chamber is defined at its upper end by a first flange on the spool and at is lower end by a shelf of the activation knob.
 14. The bidirectionally operable trimmer head of claim 3, wherein said spool at least one chamber bound between an upper flange and a lower flange, and includes a spoke extending into said chamber from said spool, and wherein said trimmer line is routed through a passageway within said spoke, and wherein the passageway into the at least one chamber.
 15. A trimmer head for use with a trimmer machine, comprising: a trimmer head having housing and a spool rotatably mounted within the trimmer head housing; said spool having a central core with an axial opening extending therein, said spool defining at least a first chamber for winding trimmer line threaded through said spool and around the spool central core in a first winding direction; said spool having at least one flange defining a first passage therein extending from the core to a first side of the spool and a second passage therein extending from the core to an opposite side of the spool from the first side of the spool; said trimmer head having a pair of eyelets for receiving the ends of the trimmer line therethrough from one eyelet through said first and second passages through said core and through said second eyelet to an area outside of the housing; an activation knob slidably connected to said trimmer head housing for moving said spool from a first axial position relative to said housing to a second axial position relative to said housing; said trimmer head having a ratchet mechanism selectively switchable between a first winding mode and a second line dispensing mode; and said spool further including a replaceable module section removably attached to said spool, wherein said module section includes a first radial module passage section having a radial passageway connecting said first and second passages for routing said trimmer line straight through said spool first and second passages in a radial direction when the first module section is in said spool aligned with said first and second chambers; and said replaceable module section includes a second non-radial module passageway section having a passageway connecting said first and second chambers for routing said trimmer line in a non-radial direction from said spool first passage to said spool second chamber when the second non-radial module section is in said spool aligned with said first and second passages.
 16. A spool for use with a string trimmer head, said spool having a central core and at least one flange extending therefrom, said spool and flange defining at least a first chamber section for winding trimmer line threaded through said spool and around the spool central core in a first winding direction; said spool having at least one flange defining a first passage therein extending from the core and through the flange to a first side of the spool and a second passage therein extending from the core and through the flange to a side of the spool opposite from the first side of the spool; said spool further includes a replaceable module section removably attached to said spool, wherein said module section includes a first radial module passageway section having a radial passageway connecting said first and second passages for routing said trimmer line straight through said spool first and second passages in a radial direction when the first module section is in said spool aligned with said first and second chambers; and said replaceable module section includes a second non-radial passageway section having a passageway connecting said first and second passages for routing said trimmer line in a non-radial direction from said spool first chamber to said spool second passage when the second non-radial module section is in said spool aligned with said first and second passages. 